Seal for the rotor of rotary piston machines

ABSTRACT

The parting line or groove between the piston halves of the rotor of a rotary piston engine are sealed by means of fools which conform to the configuration of a peripheral portion of the rotor and cover the parting line or joint.

BACKGROUND OF THE INVENTION

This invention relates to a system of sealing the piston of rotary piston engines.

Different solutions are known for achieving tightness of the piston in rotary piston engines.

In the well-known Wankel engine, a spatial system of sealing strips is arranged around the rotating piston in such a way that a springy adjusting sealing against the surrounding housing is obtained in axial and radial direction. This sealing system allows the use of the Wankel engine as an engine with the internal combustion of the Otto process,

Most of the other rotary piston engines known today do not have any springy self-adjusting sealing between the rotary piston and the surrounding housing. This renders them useless for an expansion engine in a power engine process, their use as a compression engine is state of the art.

Furthermore, types of rotary piston engines have become known the pistons of which are divided transversely to the rotating axle in such a way that the piston halves can be pressed apart by springs so that they come to rest at the side walls of the surrounding housing and thus form an area sealing. The sealing between the two piston halves is taken over by further sealing elements that are arranged in the parting line or groove area.

Rotary piston engines with pistons split in the said way can be vane cell engines or rotary piston engines.

These groups of rotary piston engines are especially the subject of the present invention. The split pistons of these groups have the property that they show a good dynamic tightness with the aforementioned sealing system in the operation of the engines. If the engines are not in operation, the static tightness is, however, only small.

The patent application DE 102006057003 A1 (granted as EP 210009 (published by WIPO as WO 2008/065017)) presents a sealing system of rotary piston engines in which the rotor consists of rotor discs arranged next to each other situated on a common rotor axle and being pressed apart by acting spring and/or gas forces in the grooves between the discs so that the front sides of the discs pointing to the side walls of the housing bear sealingly against them, thus preventing the medium from getting access to the axles. In the parting line or joint between the discs, stacks of movable shaped lamellae are mounted which adjust to the changing breadth of the joint and prevent an inner flow around the rotor.

SUMMARY OF THE INVENTION

It is an object of the present invention to increase the static tightness of the idle, not operating engine in such a way as it is obtained in engines of the stroke piston type with new, i.e., not worn, piston rings.

According to the invention this object is attained by means of foil-like covers placed from outside over the parting line or groove between the piston halves which covers can have the breadth of the two piston halves and are connected to the sealing elements for the radial sealing of the piston in such a way that the axial mobility of the piston halves towards each other is not restrained, the parting line or groove between them, however, is tightly closed around the rotary piston by fluid forces around the rotary piston.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are side views of a vane cell rotor with seals of the invention mounted theron and of one of the seals itself, respectively;

FIGS. 2A and 2B are perspective views corresponding to FIGS. 1A and 1B, respectively;

FIGS. 3A and 3B are perspective views of the rotor of a rotary piston engine of the Wankel type with a seal of the invention mounted thereon and of the seal itself, respectively; and

FIGS. 4A and 4B are perspective views of a rotary piston engine with a two-sided piston with a seal of the invention mounted thereon and of the seal itself, respectively.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1A, 1 B, 2A and 2B, two piston halves 1 a and 1 b of a rotor 1 are pressed by pressure springs inside the rotor (not shown) against the side walls of the rotor housing (not shown) and the piston halves 1 a, 1 b are sealed around the central shaft (not shown). The vanes 3 are pressed radially outward by the pressure springs 4 and seal the rotor against the housing runway. The vanes 3 have internal pressure springs, which press them simultaneously axially outward against the housing side walls. The groove between the piston halves 1 a and 1 b is covered by the sealing elements 5.

According to the invention the sealing elements are placed across the piston halves 1 a and 1 b in such a way that these can move in an axial direction and thus can keep their sealing attachment to the housing side walls.

The sealing elements 5 reach with both sides into the receiving grooves 2 in the piston halves 1 a and 1 b; they are flanged at their lower ends so that they overlap and thereby form a fluid-tight attachment for the pressure springs 4.

The sealing elements 5 consist of flexible material which is impenetrable to the fluid of the engine and at the same time has further qualities such as thermal and chemical resistance against the fluid.

The pressure springs 4, which cause the radial pressure of the radial sealing elements, at the same time cause a corresponding counter-pressure on the ends of the sealing elements 5 and thereby prevent them leaving the receiving grooves 2.

With respect to FIGS. 3 and 4, the inventive solution is identical to the solution described for the vane-cell rotor. The shape and the number of sealing elements 5, 11 and 16 are determined by the respective configuration of the piston of the rotary piston engine and the number of sides or corners of the piston. The rotor, piston halves, sealing foils, groove and vanes in FIGS. 3A, 3B are 7, 7 a and 7 b, 11, 9 and 8, respectively, and in FIGS. 4A, 4B are 13, 13 a and 13 b, 16, 14, and 15, respectively. Also, in FIG. 3A, 10 is a pressure spring under vane 8 (similar to spring 4 under vane 3 is FIG. 1A), and, in FIG. 4A, 12 a and 12 b are low-friction coatings. 

1-5. (canceled)
 6. A rotary engine comprising a rotor divided transversely to an axis of rotation of the rotor to form two piston halves which are urged apart from each other to sealingly engage side walls of a housing for the rotor and thereby form a space between the piston halves which defines a groove circumscribing the rotor, and sealing elements which seal the groove with respect to a working fluid of the engine, each of the sealing elements comprising a foil shaped to a contour of a peripheral portion of the rotor and covering the groove.
 7. The rotary engine of claim 6, wherein each of the sealing elements is of a width in an axial direction of the rotor only slightly smaller than axial width of the rotor.
 8. The rotary engine of claim 6, further comprising radial sealing elements in the form of radial vanes received in respective radial slots in the rotor and each of the vanes being urged radially outward by a spring in the radial slot, the spring being situated radially inward of the vane and having an end bearing against a radially inner end of the vane, and wherein the sealing element is bent at an end thereof to form a flange which abuts the bottom surface of the groove, and another end of the spring bears against the flange.
 9. The rotary engine of claim 8, wherein the flange of each of two adjacent ones of the sealing elements abut the bottom surface of the same one of the grooves so that the flange of one of the two sealing elements overlies the flange of the other of the two sealing elements and said other end of the spring bears against the upper of the two flanges.
 10. The rotary engine of claim 8, wherein the spring is arranged so as to retain the sealing element in the groove. 